1. Technical Field
The present disclosure relates to a packaging machine, and more particularly, to a packaging machine which automatically packages articles such as rice, sugar, salt, food for dogs or cats, or the like in packaging bags and shaping the packaging bags filled with the articles so that the packaging bags have respective thicknesses having a predetermined value.
2. Related Art
Japanese Patent Application Publication No. 2010-A-126244 discloses, as one type of the above-described packaging machine, a packaging machine which continuously produces products filled with articles by grasping an upper end of a packaging bag by grips and suspending the packaging bag, and intermittently moving to a zipper opening step, a filling step filling packaging bags with articles, a nitrogen gas filling step, a temporary sealing/deaeration/shaping step, a formal sealing step and a sealed part cooling step sequentially.
When a packaging bag filled with article differs in the thickness between an upper part thereof and a lower part thereof due to a bulging part at the bottom of the packaging bag or the like, collapsing of the packaging bags laid out flat tends to occur. In order that the packaging bag laid out flat may be prevented from collapsing, the packaging bags need to be shaped so that the packaging bags filled with articles have respective thicknesses having a predetermined value.
In the above-described conventional packaging machine, a bag opening is temporarily sealed in the temporary sealing/deaeration/shaping step so that an insertion hole for a deaeration nozzle is formed in the bag opening of the packaging bag. The packaging bag filled with the article is shaped by a shaping device so that the thickness of the packaging bag has the predetermined value, while the deaeration nozzle is inserted into the insertion hole to remove excessive air from the packaging bag.
The aforementioned shaping device includes a pair of inner and outer presser plates pressing the packaging bag from both sides of the bag, vibrators which are mounted on the respective presser plates to vibrate the respective presser plates and a receiving plate which is moved upward to receive and support the bottom of the packaging bag. In the temporary sealing/deaeration/shaping step, the receiving plate of the shaping device is moved upward to support the bottom of the packaging bag. With this, the pressing plates are simultaneously vibrated by the vibrator while the packaging bag is pressed by the pressing plates, whereby the article filling the packaging bag is vertically stretched so that the packaging bag is shaped so as to have a predetermined thickness.
In the above-described conventional packaging machine, the thickness of the packaging bag can be shaped into a predetermined value without variations when small-sized packaging bag has a capacity ranging from about 1 kg to 10 kg. However, when a large-sized bag having a capacity of 20 kg is used, for example, the conventional packaging machine requires substantial time to shape the packaging bag in order that the thickness thereof has a predetermined value without variations. Accordingly, even when the opening step, the nitrogen gas filling step and the like can be completed in a shorter time period, the production efficiency of the packaging machine would inevitably be reduced to a larger extent if the shaping step requires time.